Re: Re: [GENERAL] contrib/plantuner - enable PostgreSQL planner hints

Kevin Grittner wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> > I sometimes want to know what the planner thinks the cost of some
> > plan other than the one actually selected would be.
>
> Another DBMS I used for years had a way to turn on an *extremely*
> verbose mode for their planner; it showed everything it considered
> with its related cost information. Even a moderately complex query
> generated hundreds or thousands of lines of output, so I rarely used
> it; but for those particularly stubborn queries, where you just can't
> understand why it's picking the plan it is, a little work wading
> through the output would *always* clear up the mystery.
>
> Now that we can generate EXPLAIN output in more structured formats,
> perhaps we could think about adding an "extremely verbose" mode where
> the planner would "think out loud" as a whole separate section from
> where we show the chosen plan?

Well, we have OPTIMIZER_DEBUG, which is a compile-time flag, but that
perhaps can be changed to output as part of EXPLAIN.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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